"Growth hormone (GH) increases after exercise with a dose (intensity)-response pattern. Most studies have analyzed the GH response to lower or total body exercises, but, to our knowledge, no studies have been carried out on upper body high intensity (higher than oxygen uptake peak - VO2peak) exercise".

This study assessed the relationship between the growth hormone response to upper-body high-intensity exercise. It was hypothesized that the growth hormone response to upper-body high-intensity exercise would be associated with upper-body physical fitness. Males (N = 16) with a wide range of aerobic fitness and body compositions served as Ss. Based on VO2peak and arm cranking ergometer incremental continuous maximal exercise test results, all Ss underwent a constant power upper-body high-intensity exercise at an intensity corresponding to their 150% VO2peak. The upper-body high-intensity exercise was carried out up to exhaustion under metabolic (VO2) and cardiac (ECG) monitoring. Blood samples were collected before and after (for 90 minutes) the test to assess lactate and growth hormone concentrations.

Lactate peak, reached after ~5.8 minutes of upper-body high-intensity exercise, ranged from 9.1 to 14.8 mmol. Growth hormone peak was reached after ~27.2 minutes of exercise and ranged from 1.78 - 15.2 mg/l. Growth hormone production was moderately correlated with absolute and relative VO2peak of the maximal aerobic power test and with peak power in the upper-body high-intensity exercise.

Implication. The growth hormone response to a short term high-intensity upper-body exercise is associated with aerobic fitness but not anaerobic fitness. Lactate peak and total mechanical work are not related to the growth hormone response in upper-body high-intensity exercise.